Evidence for spatially inaccessible labile N from a comparison of soil core extractions and soil pore water lysimetry

Darrouzet‐Nardi, Anthony; Weintraub, Michael N.

doi:10.1016/j.soilbio.2014.02.010

Cited by 47 publications

(43 citation statements)

References 69 publications

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“…Of the four studies we cite that describe seasonal patterns in growing season N availability in the Arctic (Giblin et al 1991;Weintraub and Schimel 2005;Ström et al 2012;Darrouzet-Nardi and Weintraub 2014), only Darrouzet-Nardi and Weintraub (2014), who also frequently sampled soil water, described similar soil N variability to that described here. Other studies that do not show these patterns either sampled less frequently (Edwards and Jefferies 2013) or sampled organic rather than inorganic soil N (Ström et al 2012).…”

Section: Discussionsupporting

confidence: 68%

“…Plots at Imnavait were separated by <50 m. Samples at that site were collected in microsites both inside E. vaginatum tussocks and in the intertussock spaces (spaces between tussocks with little to no E. vaginatum). Data from the tussock samples are presented in a separate study comparing lysimetry with soil core extractions (Darrouzet-Nardi and Weintraub 2014). Although samples at the Imnavait site were collected for an unrelated study, they parallel the samples collected from the Toolik site in sampling year, frequency, and location (intertussock).…”

Section: Methodsmentioning

confidence: 99%

“…One of the key challenges to understanding tundra soil N availability is that it is strongly seasonal, corresponding to fluctuations in intra-annual environmental conditions (Buckeridge and Grogan 2010;Buckeridge et al 2013;Edwards and Jefferies 2013;Darrouzet-Nardi and Weintraub 2014). However, these intra-annual patterns in soil nutrient availability are not well quantified.…”

Section: Introductionmentioning

confidence: 99%

“…Determining seasonal patterns of soil N availability requires sampling at a high temporal resolution, as pulses in N may be short lived. The few studies that have sampled with high temporal frequency focused their sampling at the winter-spring transition (Larsen et al 2007;Buckeridge et al 2013;Edwards and Jefferies 2013), with fewer studies including sampling throughout the growing season (Giblin et al 1991;Weintraub and Schimel 2005;Darrouzet-Nardi and Weintraub 2014). As the timing and variability of seasonal weather events in the Arctic are predicted to change with global warming (Anisimov et al 2007), potential changes in snowpack depth, timing of spring thaw and fall freeze, and winter and growing season soil temperatures may influence both the timing and magnitude of Arctic soil nutrient availability.…”

Section: Introductionmentioning

confidence: 99%

“…In contrast, soil extractions every 2 weeks suggest peaks in extractable total free primary amines (TFPA) and (or) ammonium (NH 4 + ) in moist acidic, shrub, and wet sedge tundra soils following increases in air and soil surface temperature in late June, barely detectable levels in July, and then increases in August in some ecosystems (Weintraub and Schimel 2005). Regular sampling of soil pore water in moist acidic tundra suggests that N availability peaks of varying size and duration might also be observed at times other than thaw during the summer growing season (Ström et al 2012;Darrouzet-Nardi and Weintraub 2014). Substantial variation observed within and among plant communities suggests that differences in microsite conditions and plant phenological patterns can result in contrasting soil N dynamics between even nearby sites.…”

Section: Introductionmentioning

confidence: 99%

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Seasonal patterns of soil nitrogen availability in moist acidic tundra

et al. 2017

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Our ability to predict effects of changing soil nitrogen (N) in Arctic tundra has been limited by our poor understanding of the intra-annual variability of soil N in this strongly seasonal ecosystem. Studies have shown that microbial biomass declines in spring accompanied by peaks in inorganic nutrients. However, subsequent to this early pulse, there are few high temporal resolution measurements during the growing season. We hypothesized that (1) low N would be maintained throughout the growing season, (2) peaks of total free primary amines (TFPA), ammonium (NH 4 + ), and nitrate (NO 3 − ) would follow a sequential pattern driven by mineralization and nitrification, and (3) a peak in soil N would occur as plants senesce. We conducted weekly measurements of TFPA, NH 4 + , and NO 3 − in two tundra sites, from soil thaw in spring to freeze in fall. At each site, NH 4 + peaks were followed by smaller peaks in NO 3 − , supporting the hypothesis that excess NH 4 + would be nitrified. Furthermore, peaks in NH 4 + were observed both shortly after leaf expansion and at plant senescence. The variation in timing between sites and the peaks in NH 4 + subsequent to thaw indicates that nutrient limitation in these ecosystems is more dynamic and spatially variable than previously thought.Key words: nitrogen availability, nitrogen mineralization, seasonality, moist acidic tundra, total free primary amines.Résumé : Notre capacité à prévoir les effets de l'azote (N) changeant dans les sols de la toundra arctique a été limitée par notre compréhension insuffisante de la variabilité au cours d'une même année de N des sols dans cet écosystème fortement saisonnier. Les études ont montré des baisses de biomasses microbiennes au printemps accompagnées de pics dans les substances nutritives inorganiques. Cependant, subséquemment à cette première pulsation, il y a peu de mesures de résolution temporelle élevée pendant la saison de croissance. Nous avons formulé l'hypothèse (1) qu'un faible niveau de N serait maintenu au cours de la saison de croissance, (2)

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Section: Discussionsupporting

confidence: 68%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Seasonal patterns of soil nitrogen availability in moist acidic tundra

et al. 2017

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Permafrost collapse shifts alpine tundra to a carbon source but reduces N₂O and CH₄ release on the northern Qinghai‐Tibetan Plateau

Abbott

Zhao

et al. 2017

Geophysical Research Letters

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Important unknowns remain about how abrupt permafrost collapse (thermokarst) affects carbon balance and greenhouse gas flux, limiting our ability to predict the magnitude and timing of the permafrost carbon feedback. We measured monthly, growing‐season fluxes of CO2, CH4, and N2O at a large thermokarst feature in alpine tundra on the northern Qinghai‐Tibetan Plateau (QTP). Thermokarst formation disrupted plant growth and soil hydrology, shifting the ecosystem from a growing‐season carbon sink to a weak source but decreasing feature level CH4 and N2O flux. Temperature‐corrected ecosystem respiration from decomposing permafrost soil was 2.7 to 9.5‐fold higher than in similar features from Arctic and Boreal regions, suggesting that warmer and dryer conditions on the northern QTP could accelerate carbon decomposition following permafrost collapse. N2O flux was similar to the highest values reported for Arctic ecosystems and was 60% higher from exposed mineral soil on the feature floor, confirming Arctic observations of coupled nitrification and denitrification in collapsed soils. Q10 values for respiration were typically over 4, suggesting high‐temperature sensitivity of thawed carbon. Taken together, these results suggest that QTP permafrost carbon in alpine tundra is highly vulnerable to mineralization following thaw, and that N2O production could be an important noncarbon permafrost climate feedback. Permafrost collapse altered soil hydrology, shifting the ecosystem from a carbon sink to carbon source but decreasing CH4 and N2O flux. Little to no vegetation recovery after stabilization suggests potentially large net carbon losses. High N2O flux compared to Arctic and Boreal systems suggests noncarbon permafrost climate feedback.

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Biogeochemistry of Wetland Carbon Preservation and Flux

Neubauer

Megonigal

2021

Geophysical Monograph Series

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Evidence for spatially inaccessible labile N from a comparison of soil core extractions and soil pore water lysimetry

Cited by 47 publications

References 69 publications

Seasonal patterns of soil nitrogen availability in moist acidic tundra

Seasonal patterns of soil nitrogen availability in moist acidic tundra

Permafrost collapse shifts alpine tundra to a carbon source but reduces N₂O and CH₄ release on the northern Qinghai‐Tibetan Plateau

Biogeochemistry of Wetland Carbon Preservation and Flux

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Evidence for spatially inaccessible labile N from a comparison of soil core extractions and soil pore water lysimetry

Cited by 47 publications

References 69 publications

Seasonal patterns of soil nitrogen availability in moist acidic tundra

Seasonal patterns of soil nitrogen availability in moist acidic tundra

Permafrost collapse shifts alpine tundra to a carbon source but reduces N2O and CH4 release on the northern Qinghai‐Tibetan Plateau

Biogeochemistry of Wetland Carbon Preservation and Flux

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Permafrost collapse shifts alpine tundra to a carbon source but reduces N₂O and CH₄ release on the northern Qinghai‐Tibetan Plateau